taller tires than stock

[SLaw]

Is there a benefit going up to a 285/70 vs. Stock 265/70 size tire . I know a taller skinny tire is better in snow , I have heard going up a size will slightly help fuel mileage , is this true??

 

[EricBu12]

True a taller tire will lower RPM but if too low, it will hurt it. . if the second number is larger than the old tire, it is taller and skinnier. So a 265/70 stock is wider than a 265/85. ... MY STOCK 265/70 is wider but the same diameter as my 225/70-19. 5"... . when you look at a tire specs, look at the diameter and width. if you have 4:10 gears, taller tires will help solo running. But it will hurt towing up a hill as it reduces the ratio.

 

[EricBu12]

A 285/70 is wider and taller than a 265/70. Youd have to go to a 265/85 to be skinnier and taller.

 

[Bob V]

The first # is the WIDTH of the ties in MM, divided by 25. 4 to get inches. The second # is the aspect ratio. the height if the sidewall in a ratio of the width. to find the size in inches.

265/70-17

265 dev 25. 4 = 10. 43" wide

10. 43 X . 70= 7. 301 (height of sidewall)

7. 301X 2 (two sidewalls)=14. 602

14. 602+17"(rim diameter)=31. 602

Now different manufacturers are slightly different for the same size, and the #s are approximate.

 

[NIsaacs]

Is there a benefit going up to a 285/70 vs. Stock 265/70 size tire . I know a taller skinny tire is better in snow , I have heard going up a size will slightly help fuel mileage , is this true??

I like the 285's, they look better and carry more weight. However for me, I think I lose a little fuel milage. The best way to save fuel is slow down, but for me in the wide open spaces of the west, that is hard to do



Nick

 

[SLaw]

Did speedo need to be reclabritated when changed from stock ???

 

[Bob4x4]

Did speedo need to be reclabritated when changed from stock ???

To be accurate yes,it will be a small error with your increase in radius. Do the math as a percentage and you will know the amount of inaccuracy

 

[EDankievitch]

I'm running 285's on my 2012. they did help a small bit with the MPG's I've found that the Cooper discovery seem to offer the lowest rolling restance. ProComps the worst. But the wider size filling the wheelwells is more of a bennifit than the MPG's increase. .

 

[Bob4x4]

I'm running 285's on my 2012. they did help a small bit with the MPG's I've found that the Cooper discovery seem to offer the lowest rolling restance. ProComps the worst. But the wider size filling the wheelwells is more of a bennifit than the MPG's increase. .

Are you adjusting your math for the speedo inaccuracy ?

 

[WCPoe]

Klenger's Gear-Speed Calculator for Dodge 2500/3500 with Cummins Turbo Diesel

This gear calculator that Klenger made is a great tool for us Dodge owners. It has all the trans listed, plus you can input the tire sizes, axle ratio or overall diameter if need be. Just page down to get to your transmission and calculate away.

http://www.klenger.net/RVing/Towing_Dodge-CTD/general-reference/gear-speed-calculator.pdf

It can be found at his website as a downloadable xls spreadsheet as well, link here.


http://www.klenger.net/RVing/Towing_Dodge-CTD/index.html



Thanks KlengerOo.

 

[EdGarcia]

So I also "upgraded" my tires because I wanted a beefier look for my new 2012. I went with the 285/75/R17's because I really liked the look it gave my Ram once I got them mounted on. But I am a bit curious if anything has changed or may have been affected by going this size... other the the slight speed differences registered on the speedo.

What I mean is... is my transmission affected negatively long term at all by this tire change, does the change affect the point at which the integraded diesel exhaust brake kicks in when in use?? Will the tire change affect the exhaust brake negatively over the long term??

I've attached some photo's of my Ram with the new tires for reference.

 

[JR]

By switching to a larger wider tire, you are adding to the rotational mass therefore adding more weight. The more weight you add, the more leverage your taking away from your engine. Also by going to a taller tire, your effectively giving yourself a taller gear, which will take away from towing capacities. I agree the 285s look much better in the wheel wells, and they are much more functional for me as I am in soft terrain alot and the wider tire lightens my footprint by a little. But there is a price to pay for looks, and its in the form of less fuel mileage and less power. I would like to be able to come across a set of 4th gen wheels so that I can run a factory sized radial the majority of the time and then the 4 or 5 months out of the year Im running offroad or the snow is flying I can throw my goodyear duratrac 285s back on.



Edit: Hey Ed, sharp looking truck! I have a soft spot for white!

 

[EdGarcia]

By switching to a larger wider tire, you are adding to the rotational mass therefore adding more weight. The more weight you add, the more leverage your taking away from your engine. Also by going to a taller tire, your effectively giving yourself a taller gear, which will take away from towing capacities. I agree the 285s look much better in the wheel wells, and they are much more functional for me as I am in soft terrain alot and the wider tire lightens my footprint by a little. But there is a price to pay for looks, and its in the form of less fuel mileage and less power. I would like to be able to come across a set of 4th gen wheels so that I can run a factory sized radial the majority of the time and then the 4 or 5 months out of the year Im running offroad or the snow is flying I can throw my goodyear duratrac 285s back on.

Edit: Hey Ed, sharp looking truck! I have a soft spot for white!

Diesel4life...

Thanks for the info and insight... much appreciated! I knew I would be giving up a little power and fuel economy, but I've always wanted this truck & finally got it this year... and I wanted that awesome beefy look Rams are known for.

 

[EDankievitch]

Yes I had the speedo re calabrated. The dealer was able to just change the tire size from the 265's to the 285's. 285's are the standard tire on the Power Wagon so the size in already in the computer. I run the air pressure at 65lbs front and 60lbs rear. Larger tire more rolling restance? as far as I can tell only to get it moving once it's up to speed it hasn't been an issue. The 5% over drive that it gives seems to help on the long trips. I use to run 315's on my 05 but that was too much when towing, below 55 I had to down shift to 5th for better MPG's. I should add that on my 2012 with the 3. 73 rear end gears and the 285's tires my RPM is 1600 at 55 mph right at the lower end of the sweet spot for the 6. 7 engine. /I]

 

[Regcabguy]

Taller, wider tires look more proportionate to the vehicle and aren't that noticible powerwise with an unladen truck,but load them up. . instantly you'll feel the drag. Throw a MT tread on there and you've got more drag. They sure look sweet though.